96 lines
2.6 KiB
Go
96 lines
2.6 KiB
Go
package watch
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import (
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"fmt"
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"time"
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events "github.com/docker/go-events"
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)
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// ErrSinkTimeout is returned from the Write method when a sink times out.
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var ErrSinkTimeout = fmt.Errorf("timeout exceeded, tearing down sink")
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// timeoutSink is a sink that wraps another sink with a timeout. If the
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// embedded sink fails to complete a Write operation within the specified
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// timeout, the Write operation of the timeoutSink fails.
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type timeoutSink struct {
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timeout time.Duration
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sink events.Sink
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}
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func (s timeoutSink) Write(event events.Event) error {
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errChan := make(chan error)
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go func(c chan<- error) {
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c <- s.sink.Write(event)
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}(errChan)
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timer := time.NewTimer(s.timeout)
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select {
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case err := <-errChan:
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timer.Stop()
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return err
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case <-timer.C:
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s.sink.Close()
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return ErrSinkTimeout
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}
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}
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func (s timeoutSink) Close() error {
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return s.sink.Close()
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}
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// dropErrClosed is a sink that suppresses ErrSinkClosed from Write, to avoid
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// debug log messages that may be confusing. It is possible that the queue
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// will try to write an event to its destination channel while the queue is
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// being removed from the broadcaster. Since the channel is closed before the
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// queue, there is a narrow window when this is possible. In some event-based
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// dropping events when a sink is removed from a broadcaster is a problem, but
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// for the usage in this watch package that's the expected behavior.
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type dropErrClosed struct {
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sink events.Sink
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}
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func (s dropErrClosed) Write(event events.Event) error {
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err := s.sink.Write(event)
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if err == events.ErrSinkClosed {
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return nil
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}
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return err
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}
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func (s dropErrClosed) Close() error {
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return s.sink.Close()
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}
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// dropErrClosedChanGen is a ChannelSinkGenerator for dropErrClosed sinks wrapping
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// unbuffered channels.
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type dropErrClosedChanGen struct{}
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func (s *dropErrClosedChanGen) NewChannelSink() (events.Sink, *events.Channel) {
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ch := events.NewChannel(0)
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return dropErrClosed{sink: ch}, ch
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}
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// TimeoutDropErrChanGen is a ChannelSinkGenerator that creates a channel,
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// wrapped by the dropErrClosed sink and a timeout.
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type TimeoutDropErrChanGen struct {
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timeout time.Duration
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}
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// NewChannelSink creates a new sink chain of timeoutSink->dropErrClosed->Channel
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func (s *TimeoutDropErrChanGen) NewChannelSink() (events.Sink, *events.Channel) {
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ch := events.NewChannel(0)
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return timeoutSink{
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timeout: s.timeout,
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sink: dropErrClosed{
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sink: ch,
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},
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}, ch
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}
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// NewTimeoutDropErrSinkGen returns a generator of timeoutSinks wrapping dropErrClosed
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// sinks, wrapping unbuffered channel sinks.
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func NewTimeoutDropErrSinkGen(timeout time.Duration) ChannelSinkGenerator {
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return &TimeoutDropErrChanGen{timeout: timeout}
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}
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